bitcoin-handshake

Build a rudimentary client for the Bitcoin P2P binary protocol so we can complete the peer handshake and possibly use it as a starting point for other things.

Architecture description in ARCHITECTURE

🚀 Looking for the quickstart? Scroll to the Docker Compose section below.

Prerequisites

Install golangci-lint
Install pre-commit

Nix users can use the provided flake.nix and enter a dev shell with all dependencies in place by running:

nix develop

Editors with Direnv support/plugins (VS Code, Emacs, NeoVim) can pick up the dev shell environment and use the tools in a reproducible manner.

Tested on Linux, but the Nix setup should work on macOS too.

Installing dependencies

To install Go dependencies associated with eth-address-watch, run the command

make install

Setting up `pre-commit`

Install the git hooks to run checks before committing via pre-commit.

make local-setup

Using Code Formatters

Format code with

make codestyle

Using Code Linters

Run code linters with

make lint

Running Tests

Run tests with

make test

Running the client

The client entrypoint is main.go, which you can build and run directly, but we have several helpers.

Running the client (manual)

Local developer run, assuming you have all the dependencies, the Go toolchain and a bitcoin node running on your machine

make run

Running the client (Docker Compose)

Docker-based run -- the only dependency is a working Docker installation and Docker Compose

docker compose run client

The docker-compose.yml file defines two services:

node running a bitcoin node in regtest mode.
client running the client app.

The command above will start the node, wait for it to boot, and then run the client. You should see it connecting

❯ docker compose run client
[+] Building 0.0s (0/0)
[+] Creating 1/0
 ✔ Container bitcoin-handshake-node-1  Running
[+] Building 0.0s (0/0)
2024/04/05 14:45:55 INFO starting bitcoin-handshake
2024/04/05 14:45:55 INFO connecting to bitcoin node address=node:18444
2024/04/05 14:45:55 INFO sending handshake version message
2024/04/05 14:45:55 INFO received handshake version message
2024/04/05 14:45:55 INFO sending handshake verack message
2024/04/05 14:45:55 INFO received handshake verack message
2024/04/05 14:45:55 INFO app received message command=sendcmpct
2024/04/05 14:45:55 INFO app received message command=ping
2024/04/05 14:45:55 INFO app received message command=feefilter

The Bitcoin node is running with -debug=net, so you should be able to see the connection in its logs

❯ docker compose logs node

...

node-1  | 2024-04-05T14:45:55Z New inbound v1 peer connected: version: 70015, blocks=1, peer=1
node-1  | 2024-04-05T14:45:55Z [net] sending sendcmpct (9 bytes) peer=1
node-1  | 2024-04-05T14:45:55Z [net] sending ping (8 bytes) peer=1
node-1  | 2024-04-05T14:45:55Z [net] sending feefilter (8 bytes) peer=1
node-1  | 2024-04-05T14:45:56Z [net] socket closed for peer=1
node-1  | 2024-04-05T14:45:56Z [net] disconnecting peer=1
node-1  | 2024-04-05T14:45:56Z [net] Cleared nodestate for peer=1

You can flip to a separate console and ask the Bitcoin node for its peer state to confirm our client has connected using the getpeerinfo command. Our client uses the /MemeClient:0.0.1/ user agent.

❯ bitcoin-cli -regtest -conf="$(pwd)/.bitcoin/bitcoin.conf" getpeerinfo
[
  {
    "id": 2,
    "addr": "192.168.16.3:35492",
    "addrbind": "192.168.16.2:18444",
    "addrlocal": "192.168.16.2:18444",
    "network": "not_publicly_routable",
    "services": "0000000000000000",
    "servicesnames": [
    ],
    "relaytxes": false,
    "lastsend": 1712330273,
    "lastrecv": 1712330273,
    "last_transaction": 0,
    "last_block": 0,
    "bytessent": 247,
    "bytesrecv": 152,
    "conntime": 1712330273,
    "timeoffset": 0,
    "pingwait": 6.55446,
    "version": 70015,
    "subver": "/MemeClient:0.0.1/",
    "inbound": true,
    "bip152_hb_to": false,
    "bip152_hb_from": false,
    "startingheight": 1,
    "presynced_headers": -1,
    "synced_headers": -1,
    "synced_blocks": -1,
    "inflight": [
    ],
    "addr_relay_enabled": false,
    "addr_processed": 0,
    "addr_rate_limited": 0,
    "permissions": [
    ],
    "minfeefilter": 0.00000000,
    "bytessent_per_msg": {
      "feefilter": 32,
      "ping": 32,
      "sendcmpct": 33,
      "verack": 24,
      "version": 126
    },
    "bytesrecv_per_msg": {
      "verack": 24,
      "version": 128
    },
    "connection_type": "inbound",
    "transport_protocol_type": "v1",
    "session_id": ""
  }
]

hdeshev/bitcoin-handshake